this concept. In fact, channelologists have had this idea for some time, but a rather general experimental finding has been that standard calmodulin inhibitors that block the calcium-dependent binding of calmodulin to its target proteins do not interfere with calcium regulation of ion channels. Ching Kung and his colleagues proposed more than a decade ago (reviewed by Saimi and Kung, 1994) that...

Both intracellular calcium and transmembrane voltage cause inactivation, or spontaneous closure, of L-type (CaV1.2) calcium channels. Here we show that long-lasting elevations of intracellular calcium to the concentrations that are expected to be near an open channel (>/=100 microM) completely and reversibly blocked calcium current through L-type channels. Although charge movements associated w...

Formation of an immunological synapse (IS) between APC and T cells activates calcium entry through ORAI channels, which is indispensable for T cell activation. Successful proliferation and maturation of naive T cells is possible only if premature inactivation of ORAI channels is prevented. Although it is undisputed that calcium entry through ORAI channels is required for T cell function, it is ...

Striatal cholinergic interneurons discharge rhythmically in two patterns associated with different afterhyperpolarization timescales, each dictated by a different calcium-dependent potassium current. Single spiking depends on a medium-duration afterhyperpolarization (mAHP) generated by rapid SK currents that are associated with N-type calcium channels. Periodic bursting is driven by a delayed a...

We have studied the effect of ascorbic acid on voltage-dependent calcium channels in pancreatic beta cells. Using the whole-cell and perforated-patch variants of the patch clamp technique to record calcium tail currents, we have shown that the slowly deactivating (SD) calcium channel, which is similar to the T-type channel in other cells, is inhibited in a voltage-dependent manner by ascorbic a...

Calcium influx is an absolute requirement for the physiological acrosome reaction in sperm from all sources examined, both invertebrate and mammalian. Pharmacological studies suggest that the major channel in the sperm head plasma membrane responsible for modulating calcium entry and intracellular ionized calcium levels could be either an L-type (a class of high voltage-activated) or a T-type (...